aLIGO LHO Logbook

LHO VE (CDS, SEI, VE)

janos.csizmazia@LIGO.ORG - posted 08:38, Tuesday 06 June 2023 - last comment - 11:47, Wednesday 07 June 2023(70178)

CP8 (EX) dewar jacket pumping

I have started pumping exactly at 8:31:00.

Comments related to this report

janos.csizmazia@LIGO.ORG - 09:06, Tuesday 06 June 2023 (70180)

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Here is the stackup. The pressure was 27 microns at the start of the pumping.

Images attached to this comment

janos.csizmazia@LIGO.ORG - 13:00, Tuesday 06 June 2023 (70189)

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As we've spoken with Robert, I have generated some noise at EX, then switched the pump on/off a few times. The specifics:
Stomping (I used a steel bar, you should see a ~2 Hz noise):
- Start: 12:44:00
- Stop: 12:44:10
- Start: 12:44:40
- Stop: 12:44:50

Pump on/off sequences:
- Off: 12:46:00
- On: 12:47:00
- Off: 12:48:00
- On: 12:49:00
- Off: 12:50:00
- On: 12:51:00

The pump is now running, the pressure was 14 micron (which means, that if we could run it until Thursday, that would be sufficient - if there'll be a lock-loss, I will switch the pump off).

janos.csizmazia@LIGO.ORG - 16:33, Tuesday 06 June 2023 (70204)

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The pumping was finished at 16:23, as the data analysis haven't been finished yet.

robert.schofield@LIGO.ORG - 09:48, Wednesday 07 June 2023 (70225)

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I had a look at EX accelerometers and, while I see the pounding noise, I do not see the pump turn on and off. The accelerometers are more sensitive than DARM to vibration, so I think that it is fine to pump with this pump isolation setup while we are in observing mode.

jeffrey.kissel@LIGO.ORG - 11:47, Wednesday 07 June 2023 (70237)DetChar, ISC, OpsInfo, PEM, SYS

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Tagging a few systems level groups who should me made aware Robert's conclusion that it's OK to run these pumps.
(Not resisting, indeed supporting Robert's conclusion by making sure other people see it and have a reference to point to when it's brought up by the vacuum team.)